The metallic shield of the telephone cable is a necessary element in the cable structure in that it serves to protect the inner electric circuits from disturbing effects of enviromental electrical phenomena, such as lightning and electric power system faults. In order to carry on this important funtion the cable shield must be securely connected to ground at intervals, and interconnected at cable splices. These connections between the shield and ground, and the shield to shield connections, must be of high integrity, that is, maintaining very low connection resistance under all enviromental conditions, such as mechanical stress, vibration, thermal change, and the like; and must be capable of carrying the high surge currents which may occur from lightning or power systems faults to ground.
The present invention relates to improvements in cable shield connection devices.
There are presently available several types of cable shield connectors or "bond clamps" as they are sometimes called in the industry. However, most of them fail to provide the mechanical and electrical integrity desired. One of the difficulties heretofore experienced which contributes to failures is the inherent difficulty in engaging the thin metal shield which is closely coupled to the outer plastic cover of the cable.
The present invention avoids the difficulty of engaging the metallic shield by penetrating the outer plastic cover with the projections on an outer clamping member in cooperation with an inner base carrying a threaded stud. The projections are provided with flat contact areas which will penetrate the outer protective cover of a telephone cable and will make metal to metal contact with the metallic shield without penetrating the shield.
However, the present system positions the projections symmetrically around the threaded stud so that the outer clamp with the contact projections may be pressed toward the inner base with the projections engaging the shield at symmetrical points around the stud, and the pressure and resiliency of the material of the outer clamp will provide and maintain metal to metal contact under high resilient force to maintain the required low connection resistance under all enviromental conditions.
The flat-ended projections are adapted to penetrate through the outer plastic cover of the telephone cable and to clamp the metallic shield against the inner base without penetrating or puncturing the metallic shield.
Accordingly, it is an object of the present invention to provide an improved cable sheath connector for a telephone cable.
Another object of the present invention is to provide a cable sheath connector for a telephone cable which will maintain a low connection resistance of the cable sheath over a wide range of enviromental conditions.
Still a further object of the present invention is to provide a cable sheath for a telephone cable which will clamp the metallic shield of the cable with a high resilient force without puncturing the cable shield.
Still another object of the present invention is to provide an improved cable sheath connector assemble with a telephone cable or the like.